This invention relates to an improved craniostatic positioner hereinafter called "craniostat," particularly for the ambulatorial radiography of the temporal-mandibular articulation.
The radiographic survey of the temporal-mandibular articulation requires--as is well known to the expert in the art--a highly accurate positioning of the X-ray tube, in order to prevent interferences and the formation of images wherein different elements of the cranial structure and/or the vertebral column overlap one another. This positioning is effected by suitably tilting the collimator of the X-ray tube relatively to the patient's skull which is generally held in an erect posture.
For this purpose, conventional craniostats make use of a semicircular stand, at one end whereof there is arranged the collimator, and at the other end the cassette holder intended for receiving the radiograph sensitive plate. The half circle, which is suspended from a central pivot pin, is enabled to rotate about a perpendicular axis to its equatorial plane, and to tilt to various inclination angles by rotation in the meridian plane which contains it.
That known structure has several drawbacks, and in particular the disadvantage arising from the lack of a reference plane defined on the patient's skull, whereto the rotation and tilt angles of said craniostat stand can be related. In fact, lacking that reference, the examination repeatability, especially after some time, becomes unattainable or at least questionable owing to the patient's head being unlikely to exactly occupy each time the same position relatively to the craniostat.